Due to the requirement of retrieving a particular segment of DNA in large quantities for different purposes, scientists need an efficient way to meet their goals. Polymerase chain reactions (PCR) is one of the cost-effective and time-saving techniques which could provide billion copies of specific DNA segments in short period of time. PCR technique could be applied in many fields, such as diagnosis of diseases in hospitals and biological research institutes, identification of bacteria and viruses, detection and monitoring of diseases, genomic mutation and cancer biomarkers, inspection of environmental hazards, investigation of criminals, and so on. PCR technique only requires small amount of DNA samples extracted from blood or tissues. By utilizing fluorescent dye into the nucleic acids solutions, the amplified DNA segments could be detected through the fluorescent molecules.
Dyes and fluorescence detection technique is one of the widely adopted techniques to simultaneously detect and analyze whether the targeted nucleic acids exist in a batch of biological samples. When fluorescent signals emitted from the targeted nucleic acids which possess DNA-binding dyes or fluorescein-binding probes due to the excitation illuminated at specific wavelength, this signal indicates that the targeted nucleic acids exist. This technique has been employed for the novel PCR technique, which is called real time PCR or qPCR. Comparing to the conventional PCR technique which is end-point PCR detection, qPCR is the early-phase PCR detection with higher sensitivity and better precision. Therefore, a tool as an optical device is necessary for qPCR detection technique. The optical device has to provide a light source for exciting fluorescent probes at their specific wavelengths, and in the meanwhile, it detects the fluorescent signals emitted from the probes.
The fluorescence detection systems have been well developed in many fields, such as the application of fluorescence spectroscopy and fluorescence microscopy. By utilizing a single white light source with a set of filters and optical components, single color fluorescent probes could be easily applied. However, when the fluorescent probes with different colors are required in an assay or multiple fluorescent probes are distributed laterally for detection, it drastically increased the complexity of the fluorescence detection device, and the requirements are difficult to suffice. Moreover, even if the requirements are met, this kind of fluorescence detection device in the market is bulky and heavy, and misalignment between light sources, moveable PCR samples and detectors are also an issue.
In light of the requirements and the issues addressed above, there is a need of providing an improved fluorescence detection device for multi-color qPCR application.